A. N. Karanicolas et al., “A 15-b 1-MSample/s Digitally Self-Calibrated Pipeline ADC,” IEEE Journal of Solid-State Circuits Vol. 28, No. 12, pp. 1207-1215 (1993) discloses a digital calibration type analog-to-digital converter as a unit that can realize a high-sample rate and high-resolution analog-to-digital converter while using low power consumption. Further, Y. Shu (Y. S. Shu et al., A 15b-Linear, 20MS/s, 1.5b/Stage Pipelined ADC Digitally Calibrated with Signal-Dependent Dithering, 2006 Symposia on VLSI Technology and VLSI Circuits Session C25-1 (2006) discloses a digital calibration type analog-to-digital converter according to a scheme that uses pseudo-random signals when performing the calibration. In addition, Yun Chiu (Y. Chiu et al., “Least Mean Square Adaptive Digital Background Calibration of Pipelined Analog-to-Digital Converters,” IEEE Transactions on Circuits and Systems I Vol. 51, PP. 38-46 (2004) or Takashi Ohshima, Fast Digital Background Calibration for Pipelined A/D Converters, Institute of Electronics, Information and Communication, Technical Report of IEICE VLD 2006-138, (2007) discloses a digital calibration type analog-to-digital converter including a reference analog-to-digital converter. Just like the Yun Chiu or the Takashi Ohshima, JP-A-Hei 6(1994)-291658 discloses a digital correction type analog-to-digital converter having a high-speed low-precision analog-to-digital converter (ADC) and a low-speed high-precision ADC, which is another scheme.
The A/D converter disclosed in JP-A-Hei 6(1994)-291658 includes a high-speed low-precision ADC 10, a low-speed high-precision ADC 11, a data generation unit 12, a clock generator 13, and a divider 14 as shown in FIG. 24. The data generation unit 12 is configured so that a high-precision sampling data are selected at a timing when high-precision sampling data are output from the low-speed high-precision ADC 11, interpolation data are generated based on outputs from the low-speed high-precision ADC 11 at other timings, and the interpolation data or the low-precision sampling data from the high-speed low precision ADC 10 are selected.